Heat-conducting polymer compositions can be manufactured by mixing a powder of a metal compound such as aluminum oxide (alumina) or aluminum nitride, etc., a powder of a metal such as aluminum or copper, etc., or a metal powder whose surfaces are covered by an organic resin, with a polymer.
However, heat-conducting polymer compositions which contain a powder of a metal compound such as aluminum oxide or aluminum nitride, etc., or a metal powder whose surfaces are covered by an organic resin have an insufficient thermal conductivity. In particular, such compositions have a poor storage stability, so that the above-mentioned powders precipitate during storage. Furthermore, since heat-conducting polymer compositions which contain a powder of a metal such as aluminum or copper, etc., have electrical conductivity, the uses of such compositions are limited.